Transformer.



No. 885,034. PATENTED'APR. 21, 1908.

J. J. FRANK."

TRANSFORMER. APPLICATION FILED SEPT. 26, 1907- 2 SHEETS-SHEET 1.

\A/ITNELEISEE INVENTUR JEIH'N J'. FRANK- b q r ATTLl,

No .885,034. R v PATENTED APR. 21, 1908. v J.J.'FRANK. v

TRANSFORMER. APPLICATION FILED SEPT. 26, 1907.

2 SHEETS-SHBBT 2.

WITNhfifiEE INVENTEIR.

' I FRANK- .7 hq ATTL;

UNITED STATES PATENT OFFICE.

JOHN FRANK, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK. g

TRANSFORMER To all whom it may concern:

Be it known that I, JOHN J. FRANK; a citizen of the United States,residing at Schenectady, county of Schenectady, State of New York, haveinvented certain new and useful Improvements in Transformers, of whichthe following is a specification.

My invention relates to transformers which are especially intended forvery high voltages, and has for its object an improvement in theinsulation between the coils or the coils and the low-potentialportions, such as conductors t at a high voltage may be main:

tained without a break-down of the insulation. If, however, the highpotential stresses set up in that portion of the insulation adj acent tothe high voltage portion of the condoctors can be distributed over alarge area of the insulation surrounding the conductors, the amount ofstress to which-an portion of such insulation will be then sub ect'ed.will be less, for the intensity of the stress will be decreased as itis extended over a large area. The insulation about such'high voltageconductorswill then be less liable to be broken down than if a smallerportion of the insulation be subjected to a greater stress.

The ob'ect of minvention .is' to decrease and distribute this ighpotential stress which normally occurs over a small portion of theinsulation over a greater portion of such insulation, and thus afford abetter. rot'ection against short circuits in the transorrlner. Iaccomplish this by "surrounding the coils of high voltage conductors,which may alre'adv have their several turns insulated from adjacentturns, with parallel layers of a conducting materialiinterspersed withlayers of an insulating material; the several la ers, of conductingmaterial being insulate from each other. The conducting material thenSpecification of Letters Patent.

Application filed September 26, 1907. Serial No. 894,658.

Patented April 21, 1908..

ject to a certain potential per unit area, the

next-sheet is subject to a certain otential, but being a greater areathan the st sheet, and distant from the first sheet, the otential' erunit area is much less than t lat of the rst sheet. By employing anumber of these sheets the resulting otential stress per unit area ofthe insulation lietween the sheets, the conducting material and thefinal sheet may be made comparatively small, and thus the insulationbetween the final sheet and the conducting material adjacent to it mayeither be made small in quantity or a greater amount of a poorer qualityof insulation may be employed.

While I may accomplish the object of my invention in many ways, I preferto accomplish it bythe use of sheets consisting of a sheet of aninsulating material, such for exam le as varnished cambric, to which isattac ed by a suitable adhesive substance, such as shellac, a thin sheetof some metallic substance, for exam le tin foil. These sheets mayconsist of one ayer of cambric and one layer of tin foil, or, ifdesired, of a number of alternate layers of varnished cambric' and tinfoil to still better'equalize the otential stresses through theinsulation. lac holding the tin foil to the varnished cambrie may beomitted but I prefer to use it or some other adhesive substance forconvenience in manipulation. The compound insulatin sheet thusconstructed may then be readily formed into any of the desired shapesrequired for insulating purposes, and, if desired, any number of t usedto further increase the insulation.

In the accompan ing drawings attached'to and made a part 0 thisspecification, Figure 1 shows a vertical view ofa transformer with myimproved insulation the surrounding case and one of the coils, withportions of the insulation'shown in section to obtain a better heshelese sheets may be understanding of my invention; Fig.2 shows a topview of the same transformer, with the to and terminal bushings removed,and Fig. 3 s ows a portion of my improved insulation.

While I may employ my new method of insulation with any type oftransformer, I have shown it employed with an oil insulated coretypetransformer, in which 1 represents the base of the transformer to whichma be attached by any suitable means a shel or casing 2 to which isattached the top 3 the j omts between 1 and 2 and 2 and 3 being formedin any well-known manner, so that they be oil-tight. The cover 3 hasformed in it holes 4 and 4 to allow suitable terminals to be brought outfrom the transformer coils and other' holes, such as 4,which may beuseful and necessary forinspecting the inside of the transformer, orputting in oil etc.

5 shows the core of the transformer, which may be formed of bundles oflaminae in the well known fashion; the bundles being held together bybolts 6, passinathrough suitable crossieces 7 and fastened y nuts 8.

As t at portion of the structure of the transformer that relates to theretaining of the core and the coils, and the holding of the sametogether andto the casing is immaterial to my present invention, I shallriot further describe it; but shall confine my description to thoseportions of the transformer to which my invention relates.

9 is the primary or low-voltage winding closely fitting the core, and 10the secondary or high-voltage windin this being shown as divided intoshort 00' s, for convenience in insulatin the .coils. These short coilsare se arate from each' other by strips of an insu ating material 11,which are shown as not extending over the entire faces of the coils, butallowin spaces 12 to permit of a flow of cooling flui between the coils.I have shown the upper coils as' somewhat thicker than the lower as theinsulation between the turns ma be increased'in the well-known. mannerto urther provide against a short circuit be;- tween the several turnssubjected to the high potential between the coils.

13 are blocks of wood, which serve as suports for the coils; the insideof the coil being ined by a strip of insulating material, '14, fiber, oran other suitable substance.

Terinina s 15 are shown leading from the grimary winding throughsuitable insulating ushings 16 to the exterior of the casin of thetransformer, and terminals 17 lea ing from the secondary windingsthrough suitable high-tension bushings 18 to the .exterior of thetransformer.

Sheets of my improved insulation 19 are shown between the primary andsecondary coils; these sheets being separated by suitable insu'latinspace-blocks to makes aces 20 between -t e insulating sheets an the amle.

primary and secondary winding, through which spaces of insulating fluidmayv be allowed to flow. Insulating sheets 21 are also shown between thecoils of the transformer, the sheets being supported bv insulatingblocks 22 to provide spaces etween the sheets and the coils for thepurpose previously described. All of these sheets are shown extendingwell beyond the ends of the coils and successively greater in area asthey are s aced further from the high voltage conuctors, and sheets 21are shown as extending in a horizontal direction well beyond theexterior faces of the coils, to give a, greater voltage creepagedistance. I have also shown sheets of insulation 23 extending around theinterior of the casing of the transformer and resting upon and se matedby insulating blocks 24 and spaceb ocks 25. I These sheets 23 I haveshown as extending to the top of the casing, for while the terminals 17are shown as insulated by the hi h-voltage bushings 18, it has beenfound t at frequently a short-circuit will occur between the terminals17 and the casing and by extending' my improved insulation about thecasing, well :above the terminals 17, and makin the sheets greater inarea as they a proac the casing, I distribute and diminis the potentialstress due to the terminalsover a wide area of insulation for thereasons previously described.

In Fig. 3, I have shown a portion of my insulation consistin materialv26v attacIied to a thin conductin sheet 27; a cover of the sheet 27 be'rolle away from the insulating material. hile I have shown my insulationas consisting of one layer of conducting and one layer 'of insulatingmaterial, for greater clearness in illustration, I do not limit myselfto a single sheet in each, but a number of sheets alter nately of aconducting and an insulating material-may be used if desired, and thesema or may not be fastened together 'by an a hesive substance, such asshellac, for exile I have shown my invention as applied to a certaintype of apparatus, namely, an oil-insulated core-t e of transformer, itshould be understood t at my invention is not limited to such an aparatus, but may be used with'any type of electrical apparatus wherecertain portions are subjected to a high voltage, substantiallyrfor thepurpose and in the manner described.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,

1. In an electric device containing conof a layer of insulating ductorssubject to a high' voltage and adjacent to other conductors orconducting material, means for insulating the high-voltage conductors byinterposing between them and the low-voltage conductor or thelow-voltage conducting material adjacent to them parallel layers of aninsulating and an insulated conducting substance.

2. In an electric device containing conductors subject to a high voltageand ads j acent to other conductors or conducting ma terial, means forinsulating them from the low-voltage conductors or conducting materialby surrounding them with insulated.

sively greater in area as they are successively spaced further from thehigh-voltage conductors and spaces bet-ween the sheets containinginsulating fluid. I

4. In a transformer composed of a primary and a secondary winding,means-for decreasing and e ualizing the potential stresses due to one oft e windings over a large area of the insulation between the windings. l

5. In a transformer composed of a primary and a secondary winding, onewinding having high potential in certain portions, a laminated core andan inclosing casing, means for decreasing and equalizing the otentialstresses due to a portion of one of t e windings over a lar e area ofthe insulation be tween said win ing, the core and the casing. 6. In atransformer composed of a primary and a secondary winding with alaminated core and aninclosing casing, and high-potential terminalsadjacent to the sides of the casing, means for decreasing and equalizingthe potential stresses due to said terminals over a large area of theinsulation of said casm 7. a transformer composed of a primary and asecondary winding, one of the windings having high potential in certainportions, an insulation composed of a plurality of parallel layers of aninsulated conducting substance, and an insulating substance fordecreasing the potential stresses due to one of said windings a iid eualizing them over a large portion of the lnsu ation between saidwindlngs.

8.. In a transformer composed of a primary and a secondary winding witha laminated core and an inclosin casing, an nsulatlon composed of aplurality of arallel layers of an insulated conducting su stance, and aninsulating substance for decreasing the potential stresses due to one ofsaid windings,

and equalizing them over a large area of the insulation between .saidwinding, the core and the casing. L

9. In a transformer composed of a primary and a secondary winding, oneof the windings having high potential in certain portions, an insulationcomposed of a plurality of parallel layers of an insulated conductinsubstance,

and an insulating substance, the ayers being successively greater inarea as they are successively spaced further from the high-voltagewinding, for decreasin the potential stresses due to one of sai windingsand equalizing the stresses over a large portion of the insulationbetween said windings.

10. In a transformer composed of a primary and a secondary winding witha laminated core and an inclosing casing, an insulation composed of aplurality of arallel layers of an insulating conducted substance and aninsulating substance, the layers being successively greater in area asthey are successively spaced further from the high-voltage conductorsfor decreasing the otential stresses due to one of said windings andequalizing the stresses over a large area of the insulation between thesaid winding, the

core and the casing. 11. In a transformer composed of a primary and asecondary winding with a laminated coreand an inclosing casing, andhighpotential terminals adjacent to the sides of the casing, aninsulation composed of a plurality of 'parallel layers of an insulatedconducting substance and an insulating substance for decreasing thestresses due to the potential of said terminals and equalizing thestresses over a large area of the insulation ad'acent to the casing.

12. n a transformer composed of a primary and a secondary winding with alaminated core and an inclosing casing and highpotential terminalsadjacent to the sides of the casing, an insulation composed of aplurality of parallel layers of an insulated conducting substance and aninsulating substance, the layers being successively greater in area asthey are successively spaced further from the high-potential terminalsfor decreasing the stresses due to the otential of said terminals andequalizing t e stresses over a large area of the insulation adjacent tothe casing.

13. The combination witha transformer consisting of a primary and asecondary windin of an insulating material inclosing said 'COIlSconsisting of parallel layers of an insulating and a conductingsubstance.

14. The combination with a transformer consisting of a primary and asecondary Winding, a 'core and an inclosin casing, of an insulationcomposed of a plura ity of parallel layers of an insulating and aconducting material, the layers being successively greater in area asthey are successively spaced further from the high-voltage conductors,and spaces of a core,

between said layers filled with an insulating fluid for increasing theinsulation.

15. In a core-'type transformer consisting of .a core, primary andsecondary windings inclosing the legs of said core substantially as saidcoils, the layers being successively greater in area as they aresuccessivel spaced further from the high-voltage con uctors to decreasethe potential stresses between said coils and equalize the stressesovera wide area of the insulation separating said coils.

16. In a core-type transformer consisting primary and secondary windingsinclosing t e legs'of said core substantially as shown, one of saidwindings having a maxir'nunf potential at certain portions, and aninclosin casing, an insulatin material comosed o a plurality of aral ellayers of an insulated conducting 's'u stance and' an insulatingsubstance, the layers being successively greater in areaas they aresuccessively spaced further from the high-voltage conductors to decreasethe'potential stresses due to the high potential of one of saidwindingsand equalize the stresses over a large area of the insulation betweensaid windmg, the core and the easing. 7

17. In a core-type transformer consisting )of a core, primary andsecondary windings inclosing the legs of said core substantially asshown, and high-potential terminals adj acent to said casing, aninsulatin material consisting of a plurality of paralle layers of aninsulated conducting substance and an insulating substance, the layerssurrounding the inner srde'of said casing and being successively greaterin area as they are successively spaced further from the high voltageconductors, for decreasin the potential stresses due to said termina sand equalizing the stresses over a wide area of the insulation adjacentthe casing.

18. In combination with an oil insulated core-type transformer with acore, primary and secondary windings upon the legs of said core, aninclosing casing, high-voltage terminals brought out adjacent to thesides of JOHN J. FRANK,

Wit esses:

ELEN 'ORFORD, BENJAMIN B. HULL.

